Snowflake why hexagonal

His was alluded to, but I think it could use a bit more extrapolation. The image above shows an oxygen atom bonding with two hydrogen atoms water. We can call these covalent bonds for our purposes, although hydrogen bonds tend, in some cases and especially water have special properties that make it unique from other covalent bonds.

The result of this bond is a slightly negative charge near the oxygen atom and slightly positive near the hydrogens. What happens next is that two water molecules will build up in a specific way, relating to their charge:. This happens naturally, since when water freezes, it forces the molecules to get closer together but interestingly enough, the end result makes ice less dense than its liquid form.

As these molecules build up, you start seeing a crystal lattice:. With each ring in the crystal lattice having six side. Each point is an oxygen atom. Each side is side is a hydrogen bonding with an oxygen. The snow flake, is just this bonding happening many many times.

When the one molecule of Neo's answer change the direction a bit, the chain of all molecules move. This may bring the phenomenon like kaleidscope. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Why do snowflakes form into hexagonal structures? Ask Question. Asked 7 years, 6 months ago. Active 1 year, 7 months ago. Viewed 16k times. The image below shows a variety of such structures that are possible although by all means not an exhaustive list : What is the mechanism for snowflakes forming into these delightful symmetric hexagonal structures?

Improve this question. Kenshin Kenshin 7, 10 10 gold badges 39 39 silver badges 80 80 bronze badges. Can you please elaborate on a why the crystalline structure ice is "six-fold" and what that means, and b how the crystalline structure give arise to the shape of the above crystals and why each crystal as a unique shape?

The wikipedia article isn't really clear on these issues, but if you can interpret that page and post as an answer I will accept. It doesn't answer why the arms grow in a hexagonal shape. You could say "because the microstructure is hexagonal", but that doesn't answer the question very deeply does it?

Why does the hexagonal microstructure lead to the arms grwoing in the same way? Maybe the superficial wikipedia article is enough for you, but certainly it is not enough for me. Take 10, snowflake pictures and show the 12 that are most beautiful.

Answer originally posted October 21, Sign up for our email newsletter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options.

Discover World-Changing Science. Miriam Rossi, a professor of chemistry at Vassar College, offers the following reply: Snowflakes are symmetrical because they reflect the internal order of the water molecules as they arrange themselves in the solid state the process of crystallization.

Get smart. Sign Up. Support science journalism. Knowledge awaits. See Subscription Options Already a subscriber? The first example at right shows three views of a capped column. The first view is from the side, showing the central column and the two plates edge-on. The other two views show the same crystal from one end, with the microscope focused separately on the two plates. Double Plates A double plate is basically a capped column with an especially short central column.

The plates are so close together that inevitably one grows out faster and shields the other from its source of water vapor. The result is one large plate connected to a much smaller one. These crystals are common -- many snowflakes that look like ordinary stellar plates are actually double plates if you look closely. The first picture at right shows a double plate from the side.

The second picture shows a double plate with the microscope focused on the smaller plate. In the third picture, note the slightly out-of-focus hexagon that is about one-sixth as large as the main crystal. This hexagon is the second side of a double plate, connected to the main plate by a small axle.

Split Plates and Stars These are forms of double plates, except that part of one plate grows large along with part of the other plate. The picture at right shows all eight ways to make a split star. Split plates and stars, like double plates, are common but often unnoticed. You may have to stare at these pictures a bit to see how the two distinct pieces fit together. Note how in each case the crystals are connected in the center with short axles. Triangular Crystals Plates sometimes grow as truncated triangles when the temperature is near -2 C 28 F.

If the corners of the plates sprout arms, the result is an odd version of a stellar plate crystal. These crystals are relatively rare. Surprisingly, no one knows why snow crystals grow into these three-fold symmetrical shapes.

Note however that the molecular structure of triangular crystals is no different from ordinary six-sided crystals. The facet angles are all the same. The two end-plates are both six-branched crystals, but one is rotated 30 degrees relative to the other. This is a form of crystal twinning, in which two crystals grow joined in a specific orientation.

These crystals are quite rare, but sometimes a snowfall will bring quite a few. The picture at the far right shows a sider where the two halves are widely separated. Bullet Rosettes The nucleation of an ice grain sometimes yields multiple crystals all growing together at random orientations. When the different pieces grow into columns, the result is called a bullet rosette. These polycrystals often break up to leave isolated bullet-shaped crystals. Sometimes a bullet rosette can become a capped rosette, as shown in the example at the far right.

Radiating Dendrites When the pieces of a polycrystal grow out into dendrites, the result is called a radiating dendrite also called a spatial dendrite. The first example on the right shows radiating plates. The second example shows a fernlike stellar dendrite with two errant branches growing up out of the main plane of the crystal. Rimed Crystals Clouds are made of countless water droplets, and sometimes these droplets collide with and stick to snow crystals. The frozen droplets are called rime.

All the different types of snow crystals can be found decorated with rime. When the coverage is especially heavy, so that the assembly looks like a tiny snowball, the result is called graupel.

The first two pictures at right have relatively light rime coverage. The final example is completely covered with rime, but you can still see the six-fold symmetry of the underlying stellar crystal.